Shoes are known which have perforated soles which allow vapor permeation due to the presence of membranes which are waterproof and permeable to water vapor and are arranged so as to cover the perforations and are sealed to the sole so as to prevent water from entering the shoe through the perforations.
Shoes are also known which have soles which expel the humid air contained in the shoe by means of forced suctions produced by means of pumps actuated within the sole by way of the movement of the foot (compression and decompression).
One of these shoes is disclosed for example in patent EP 1127505.
Shoes provided with pumping devices, however, suffer the severe drawback of having a mechanical actuation and therefore of not working when no walking occurs.
Moreover, they force the inflow of external air due to the depression or suction that the pumping devices, when actuated, produce inside the shoe, a situation which should be avoided in winter or in cases of high humidity in the environment.
The inflow of cold or very humid air is certainly not healthy for the feet.
Moreover, it should be noted that this exchange of air is quite often rendered useless due to the layers of polymeric material which are arranged below the sole of the foot to create sealed pads capable of performing the pump effect, like known pumps for inflating PVC beach mattresses.
These non-vapor permeable layers create condensation and prevent the insole in contact with the foot from drying despite air recirculation.
This problem can be observed for example in patent application US2006/0143943.